Fully rotatable shuttle

ABSTRACT

A shuttle body  3  having aloop seizing beak  10  for seizing a needle thread  9  is rotatably attached to a shuttle race body  2 , pressed by a driver  4 , and continuously rotated in a rotation direction B in synchronization with vertical motion of a needle  8 . A bobbin case  5  in which a bobbin thread  12  wound around a bobbin  5  is accommodated is attached to the shuttle body  3 . Under a state where the bobbin thread  12  is pulled out from the bobbin case  5 , the shuttle body  3  is rotated, the needle thread  9  is seized by the loop seizing beak  10 , the loop of the needle thread  9  is expanded along the outer face of the shuttle body  3 , the loop of the needle thread  9  is passed over the shuttle body  3  and the bobbin case  5  so that the shuttle body  3  and the bobbin case  5  are passed through the loop of the needle thread  9 , whereby the needle thread  9  is wound around the bobbin thread  12  and a stitch can be formed.

TECHNICAL FIELD

The present invention relates to a full rotary hook which is disposed ina domestic sewing machine, an industrial sewing machine or the like.

BACKGROUND ART

A typical horizontal full rotary hook of the conventional art has a looptaker which is rotated about a rotation axis perpendicular to the axisof a movement path of a needle that is vertically reciprocated; anbobbin case holder which is attached to the inside of the loop taker; abobbin case which is detachably attached to the inside of the bobbincase holder; and a bobbin around which a bobbin thread is wound andwhich is then attached to the inside of the bobbin case.

The loop taker has a peripheral wall having a loop seizing beak forseizing a needle thread passed through a needle, and a track grooveformed in an inner peripheral portion thereof; a bottom wall connectedto one axial end portion of the peripheral wall so as to beperpendicular thereto; and a boss which is integrally formed with thebottom wall so as to be protruded from the bottom wall toward the sideopposite to the peripheral wall and is fixed to the lower axis of asewing machine with being positioned in the circumferential direction.In order to avoid interference with the inserted needle, a notch isformed in the peripheral wall of the loop taker to divide the loop takerin the circumferential direction. The loop seizing beak is formed in onecircumferential end portion which is an end portion on the downstreamside in the rotation direction of the loop taker.

The bobbin case holder has a peripheral wall having a track projectionformed on the outer periphery thereof; a bottom connected to one axialend of the peripheral wall so as to be perpendicular thereto; a flangeconnected continuously projected in the radial direction outwardly fromthe other axial end of the peripheral wall; and a stud standing from thecenter of the bottom to the open end of the inner bobbin case so as tobe perpendicular to the bottom. In order to enable the thread passingwhich will be described later, the track projection is divided along thecircumferential direction in the region where the needle is to beinserted. A holder stop recess is formed in the flange. The bobbin caseholder is attached to the loop taker under a state where the bottom isplaced on the loop taker bottom wall side. The track projection isfitted into the track groove of the loop taker, and the bobbin caseholder is rotatably supported with respect to the loop taker. Aprojection of a holder stop member fixed to the body of the sewingmachine is fitted into the holder stop recess, thereby preventing thebobbin case holder from being rotated in accordance with the rotation ofthe loop taker, in the same direction.

The bobbin case has a peripheral wall on which a bobbin thread tensionspring is disposed, and an end wall perpendicularly which isperpendicularly continuous from one axial end of the peripheral wall,and in which a latch mechanism is disposed. Under a state where thebobbin around which the bobbin thread is wound is accommodated, thebobbin case is engagingly attached to the stud of the bobbin case holderby the latch mechanism. The bobbin thread accommodated in the bobbincase is pulled out from the bobbin, passed between the peripheral wallof the bobbin case and the bobbin thread tension spring, and then guidedto the upper side through the open end of the bobbin case holder.

The horizontal full rotary hook is configured in the following manner.The loop taker is rotated about the rotation axis, the needle threadsupplied by the needle which is reciprocated in synchronization with therotation of the loop taker is seized by the loop seizing beak, and aloop of the needle thread is passed over the periphery while beingexpanded along the outer face of the bobbin case holder, therebyperforming the thread passing so as to cause the bobbin case holder topass through the loop of the needle thread. The needle thread is woundaround the bobbin thread pulled out from the bobbin. Under this state,the needle thread is pulled up due to an upward motion of a threadtake-up lever (not shown), whereby sewing a workpiece on a throat plateis allowed.

Another typical conventional art is an oscillating loop taker which has:a shuttle race body which is fixed to the body of a sewing machine; ashuttle body which is attached to the inside of the shuttle race body; adriver which is swung about a rotation axis perpendicular to the axis ofa needle that is vertically reciprocated; a bobbin case which isdetachably attached to the inside of the shuttle body; and a bobbinaround which a bobbin thread is wound and which is then attached to theinside of the bobbin case.

In the shuttle race body, a track groove which elongates in thecircumferential direction is formed in an inner peripheral portion. Theshuttle body has: a peripheral wall which elongates along a semi-arc; abottom wall which is continuous from one axial end portion of theperipheral wall; and a stud which protrudes from the bottom wall towardthe other axial end of the peripheral wall. A track projection is fittedinto the track groove of the shuttle race body, and the shuttle body isrotatably supported with respect to the shuttle race body.

The driver has the driver body which elongates along a semi-arc, and aboss which is formed integrally with the driver body, and which is fixedto a lower shaft of the sewing machine with being positioned in thecircumferential direction. The driver is configured so that the driverbody is placed at a position which is shifted by about 180 deg. withrespect to the shuttle body in the shuttle race body, and thecircumferential ends of the driver body can press the circumferentialends of the peripheral wall of the shuttle body, respectively.

The bobbin case has a peripheral wall on which a bobbin thread tensionspring is disposed, and an end wall which is perpendicularly continuousfrom one axial end of the peripheral wall, and in which a latchmechanism is disposed. Under a state where the bobbin around which thebobbin thread is wound is accommodated, the bobbin case is engaged withthe stud of the shuttle body by the latch mechanism so as to berotatably attached to the shuttle body. The bobbin case is prevented bythe shuttle race body from being rotated in accordance with the rotationof the shuttle body. The needle thread accommodated in the bobbin caseis pulled out from the bobbin, passed between the peripheral wall of thebobbin case and the bobbin thread tension spring, and then guided to theupper side through the other end side in the axial direction of theshuttle body.

The oscillating loop taker is configured in the following manner. Thedriver is swung so as to make a half rotation around the rotation axis.The shuttle body is pressed by the driver to be swung between a positionwhere a loop seizing beak is placed upwardly, and that where the loopseizing beak is placed downwardly. The needle thread supplied by theneedle which is reciprocated in synchronization with the swing operationof the shuttle body is seized by the loop seizing beak, and a loop ofthe needle thread is passed over the periphery of the shuttle body whilebeing expanded along the outer face of the shuttle body, thereby causingthe loop of the needle thread to be passed over the periphery of thebobbin case to perform the thread passing. The needle thread is woundaround the bobbin thread pulled out from the bobbin. Under this state,the needle thread is pulled up due to an upward motion of a threadtake-up lever (not shown), whereby sewing a workpiece on a throat plateis allowed.

In the horizontal full rotary hook of the conventional art, the loop ofthe needle thread is passed over the bobbin case holder by the looptaker on which the loop seizing beak is formed, in such a manner thatthe loop is passed over the periphery of the bobbin case holder to whichthe bobbin case is attached. The loop taker for seizing the needlethread and moving the loop of the needle thread is fixed to the lowershaft of the sewing machine, and hence cannot be passed through the loopof the needle thread. The loop of the needle thread is wound around athread separating portion which is an end portion of the trackprojection on the upstream side in the rotation direction of the looptaker. The two thread portions of the loop of the needle thread whichvertically elongate are separated into the bottom side and open end sideof the bobbin case holder, respectively, and passed over the bobbin caseholder.

When the lowest end of the loop of the needle thread is passed over thelowest end of the bobbin case holder, a thread portion which upwardlyelongates from the loop taker open end side of theloop-seizing-beak-forming-portion where the loop seizing beak is formed,immediately after the thread is seized by the loop seizing beakelongates toward the bottom of the bobbin case holder, and anotherthread portion which upwardly elongates from the loop taker bottom sideof the loop-seizing-beak-forming-portion immediately after the thread isseized by the loop seizing beak elongates toward the open end of thebobbin case holder. Therefore, the loop of the needle thread is passedover the bobbin case holder under a state where the loop crosses abovethe bobbin case holder. As described above, in the horizontal fullrotary hook in which the loop taker for moving the needle thread cannotbe passed through the loop of the needle thread, the loop of the needlethread crosses above the bobbin case holder when the loop is passed overthe bobbin case holder, and hence the needle thread is easily twisted.

In the oscillating loop taker of the conventional art, the loop of theneedle thread is passed over the bobbin case by the shuttle body onwhich the loop seizing beak is formed. The shuttle body which seizes theneedle thread and moves the loop of the needle thread is formedseparately from the driver which is fixed to the lower shaft of thesewing machine, and hence can be passed through the loop of the needlethread. The two thread portions of the loop of the needle thread whichvertically elongate are separated into the bottom side and open end sideof the shuttle body, respectively, and the shuttle body is passedthrough the loop of the needle thread. In accordance with this, thethread passing is performed so that the bobbin case is passed throughthe loop of the needle thread.

In the thus configured oscillating loop taker, when the lowest end ofthe loop of the needle thread is passed over the lowest end of thebobbin case, a thread portion which upwardly elongates from the shuttlebody open end side of the loop-seizing-beak-forming-portion where theloop seizing beak is formed, immediately after the thread is seized bythe loop seizing beak elongates toward the open end of the shuttle body,and another thread portion which upwardly elongates from the shuttlebody bottom side of the loop-seizing-beak-forming-portion immediatelyafter the thread is seized by the loop seizing beak elongates toward theopen end of the shuttle body. Therefore, the loop of the needle threadis passed over the shuttle body and the bobbin case with being expandedinto a substantially U-like shape without crossing in an Intermediateportion. In the oscillating loop taker in which the shuttle body formoving the needle thread can be passed through the loop of the needlethread as described above, the loop of the needle thread does not crossunlike the above-described horizontal full rotary hook, and hence theneedle thread is not twisted.

In the oscillating loop taker which can solve the problem of thehorizontal full rotary hook, since the driver which presses the shuttlebody is rotated so as to make a half rotation, and the driver must stoptwo times during an operation of one cycle, and hence it is difficult toimprove the operation speed.

Therefore, it is an object of the invention to provide a full rotaryhook which enables a needle thread to be wound around a bobbin threadwithout being twisted, and which can improve the operation speed.

DISCLOSURE OF INVENTION

The invention set forth in claim 1 is a full rotary hook comprising:

a shuttle race body which is fixed to a body of a sewing machine and hasa track groove formed on an inner peripheral portion of the shuttle racebody so as to circumferentially elongate in a circumferential directionthereof;

a shuttle body having a track projection elongating in thecircumferential direction and being divided in the circumferentialdirection, formed on an outer peripheral portion, which track projectionis fitted into the track groove to rotatably attach the shuttle body tothe shuttle race body, and in which a loop-seizing-beak-forming-portionis formed, the loop-seizing-beak-forming-portion including a loopseizing beak formed at a tip end thereof, for seizing a needle threadsupplied by a needle which is vertically reciprocated;

a driver which is continuously rotated in synchronization with avertical motion of the needle in a predetermined rotation direction, forrotating the shuttle body about an axis of the shuttle body by pressingthe shuttle body by rotation of the driver; and

a bobbin case for accommodating bobbin thread, being detachably attachedto the shuttle body,

wherein the loop-seizing-beak-forming-portion is formed so as toprotrude in a rotation direction of the shuttle body from onecircumferential end of the track projection which is placed on adownstream side in the rotation direction of the shuttle body,

in the shuttle race body, a protrusion which protrudes in an axialdirection of the shuttle race body so as to face the track groove isformed, and a recess which extends in the circumferential direction isformed on a radial outer side of the protrusion,

the track projection of the shuttle body has an inner peripheral portionand an outer peripheral portion, the outer peripheral portion moreprotruding toward an open end of the shuttle body than the innerperipheral portion, a protrusion being formed by the outer peripheralportion, and a recess which elongates in the circumferential directionbeing formed on a radial inner side of the protrusion,

the protrusion of the shuttle race body is fitted into the recess of thetrack projection of the shuttle body, the protrusion of the shuttle bodybeing fitted into the recess of the shuttle race body, and engaged withthe protrusion of the shuttle race body from a radial outer side of theshuttle body, in the outer peripheral portion of the track projection, aprojection amount with respect to the inner peripheral portion inregions near circumferential ends is smaller than a projection amountwith respect to the inner peripheral portion in a region of acircumferential intermediate portion which is between the regions nearthe circumferential ends, and the loop seizing beak is formed in a planeincluding an end face on a shuttle body open end side in the region ofthe circumferential intermediate portion of the outer peripheral portionof the track projection, and

the loop-seizing-beak-forming portion which more protrudes toward theshuttle body open end than the regions near the circumferential ends ofthe outer peripheral portion of the track projection is passed through arecess formed in the needle.

According to the invention, the shuttle body having the loop seizingbeak for seizing the needle thread is attached to the shuttle race bodyto be rotatable, pressed by the driver, and continuously rotated in thepredetermined rotation direction in synchronization with the verticalmotion of the needle. The bobbin case accommodating the bobbin thread isattached to the shuttle body. Under a state where the bobbin thread ispulled out from the bobbin case, the shuttle body is rotated, the needlethread is seized by the loop seizing beak, the loop of the needle threadis expanded along the outer face of the shuttle body, and the loop ofthe needle thread is passed over the bobbin case so that the bobbin caseis passed through the loop of the needle thread, whereby the needlethread is wound around the bobbin thread and a stitch can be formed. Theshuttle body which seizes the needle thread and moves the loop of theneedle thread while expanding the loop is rotated by the driver which isseparately formed. When the loop of the needle thread is to be passedover the bobbin case, therefore, the loop can be passed over the shuttlebody. Consequently, the loop of the needle thread can perform the threadpassing under a state where the loop is expanded into a substantiallyU-like shape without crossing in an intermediate portion, and the needlethread is wound around the bobbin thread without forming a twist.Furthermore, the driver is continuously rotated in a predeterminedrotation direction, and in accordance with the rotation, the shuttlebody is continuously rotated. The driver and the shuttle body do notstop during an operation of one cycle, and hence the full rotary hookcan be operated at a high speed.

The track projection has the inner peripheral portion and the outerperipheral portion, and the outer peripheral portion protrudes towardthe shuttle body open end with respect to the inner peripheral portionto form the protrusion. In the outer peripheral portion of the trackprojection, the projection amount with respect to the inner peripheralportion in the regions near the circumferential ends is smaller than theprojection amount with respect to the inner peripheral portion in theregion of the circumferential intermediate portion which is between theregions near the circumferential ends. Theloop-seizing-beak-forming-portion is formed so as to protrude in therotation direction of the shuttle body from the one circumferential endof the track projection which is placed on the downstream side in therotation direction of the shuttle body. Theloop-seizing-beak-forming-portion functions also as the track projectionwhich is fitted into the track groove. The loop seizing beak formed atthe tip end of the loop-seizing-beak-forming-portion is formed in theplane including the end face on the shuttle body open end side in theregion of the circumferential intermediate portion of the outerperipheral portion of the track projection.

As described above, the regions near the circumferential ends of theouter peripheral portion of the track projection are formed so as tohave a small width and a small projection amount toward the shuttle bodyopen end. According to this configuration, the needle which isvertically moved in the vicinity of the track projection is preventedfrom interfering with the shuttle body. Although the loop seizing beakis formed in the plane including the end face on the shuttle body openend side in the region of the circumferential intermediate portion ofthe outer peripheral portion of the track projection, and theloop-seizing-beak-forming-portion protrudes toward the shuttle body openend, the loop-seizing-beak-forming-portion is passed through the recessformed in the needle, and hence does not interfere with the needle.

In the shuttle race body, the protrusion is formed so as to protrudetoward the track groove, and the recess is formed on the radialouter'side of the protrusion. In the track projection of the shuttlebody, the protrusion is formed by the outer peripheral portion, and therecess is formed on the radial inner side of the protrusion. Theprotrusion of the shuttle race body is fitted into the recess of thetrack projection of the shuttle body, and the protrusion of the trackprojection of the shuttle body is fitted into the recess of the shuttlerace body, and engaged with the protrusion of the shuttle race body fromthe radial outer side. Under this state, the track projection of theshuttle body is fitted into the track groove of the shuttle race body.The track projection of the shuttle body, in which the projection amountin the regions near the circumferential ends of the outer peripheralportion of the track projection is formed so as to be small in order toavoid interference with the needle, is guided by the portion facing thetrack groove of the shuttle race body, and the shuttle body is rotatableabout its axis. Furthermore, the shuttle body is prevented fromvibrating in a radial direction during rotation, and can be stablyrotated.

The invention set forth in claim 2 is characterized in that, in theconfiguration of the invention set forth in claim 1, the shuttle bodyhas a spring member which is fixed in a vicinity of a basal end, and

the driver presses a free end of the spring member or a vicinity of thefree end.

According to the invention, the driver presses the free end of thespring member of the shuttle body or the vicinity of the free end, therotation force of the driver is transmitted to the shuttle body via thespring member, and the shuttle body is rotated. As a result, when thedriver is continuously rotated, the spring member periodically repeatsan elastically deforming operation and an operation of recovering theelastic deformation. This causes the driver and the free end of thespring member or the vicinity of the free end to periodically abutagainst and separate from each other. When the loop of the needle threadis to be passed over the shuttle body, the loop can be passed throughthe gap between the driver and the free end of the spring member or thevicinity of the free end during a period when the driver and the freeend of the spring member or the vicinity of the free end are separatedfrom each other. When the loop of the needle thread is to perform thethread passing, therefore, the needle thread can be prevented from beingpressed between the shuttle body and the driver to be caught thereby,and the loop of the needle thread can smoothly perform the threadpassing. Even when the needle thread is accidentally pressed between theshuttle body and the driver, the needle thread elastically deforms thespring member and can be then passed between the driver and the springmember. Therefore, a breakage of the needle thread does not occur.

The invention set forth in claim 3 is characterized in that, in theconfiguration of the invention set forth in claim 1, a rotation axis ofthe driver is eccentric with respect to a rotation axis of the shuttlebody.

According to the invention, the eccentricity between the rotation axesof the driver and the shuttle body causes the position where the driverpresses the shuttle body to be changed in the radial direction of theshuttle body, so that the torque transmitted from the driver to theshuttle body is periodically changed. As a result, at a time when thetorque is low, the loop of the needle thread is allowed to pass betweenthe driver and the shuttle body.

The invention set forth in claim 4 is characterized in that, in theconfiguration of the invention set forth in claim 1, the shuttle bodyhas a peripheral wall on which the track projection is formed, and aneedle drop hole is formed in a region of the peripheral wall where theneedle is to be inserted.

According to the invention, the shuttle body has the peripheral wall onwhich the track projection is formed, and the loop of the needle threadseized by the loop seizing beak is moved along the periphery of theshuttle body while being guided and expanded by the peripheral wall, sothat the loop of the needle thread can be easily passed over the shuttlebody and the bobbin case. The needle drop hole into which the needle isto be inserted is formed in the peripheral wall, thereby preventing theneedle and the shuttle body from interfering with each other.

BRIEF DESCRIPTION OF DRAWINGS

Other and further objects, features, and advantages of the inventionwill be more explicit from the following detailed description taken withreference to the drawings wherein:

FIG. 1 is a section view showing a full rotary hook 1 of an embodimentof the invention.

FIG. 2 is a front view of the full rotary hook 1.

FIG. 3 is a front view of a shuttle body 3.

FIG. 4 is a side view of the shuttle body 3.

FIG. 5 is a plan view of the shuttle body 3.

FIG. 6 is a rear view of the shuttle body 3.

FIG. 7 is a horizontal section view showing a shuttle race body 2 andthe shuttle body 3 in a simplified manner.

FIG. 8 is a graph showing abutment and separation relationships betweena driver 4 and a spring member 35.

FIG. 9 is a section view enlargedly showing a section IX of FIG. 7.

BEST MODE FOR CARRYING OUT THE INVENTION

Now referring to the drawings, preferred embodiments of the inventionare described below.

FIG. 1 is a section view showing a full rotary hook 1 of an embodimentof the invention, and FIG. 2 is a front view showing the full rotaryhook 1 as seeing from the left side of FIG. 1. The full rotary hook 1has a shuttle race body 2, a shuttle body 3, a driver 4, a bobbin case5, and a bobbin 6. The full rotary hook 1 is placed below a throat platedisposed on a sewing machine bed (not shown). The shuttle race body 2 isfixed to the body of a sewing machine, and a track groove 7 whichelongates in the circumferential direction of the shuttle race body isformed in an inner peripheral portion thereof. The shuttle body 3 has aloop seizing beak 10 for seizing a needle thread 9 supplied by a needle8 which is vertically reciprocated, and a track projection 11 whichelongates in the circumferential direction of the shuttle body 3 isformed in an outer peripheral portion thereof. The track projection 11is fitted into the track groove 7, and the shuttle body is rotatablyattached to the shuttle race body 2. The driver 4 is continuouslyrotated in a predetermined rotation direction A in synchronization withthe vertical motion of the needle 8, and presses the shuttle body 3 bymeans of the rotation, thereby rotating the shuttle body. The bobbincase 5 is detachably attached to the shuttle body 3. A bobbin thread 12is wound around the bobbin 6, and the bobbin is then attached to thebobbin case 5, so that the bobbin thread 12 is accommodated in thebobbin case 5.

The shuttle race body 2 is fixed in a horizontally placed state so thatits axis L1 is perpendicular to an axis L2 of a movement path of theneedle 8 which is vertical. The track groove 7 elongates about the axisL1 in the circumferential direction, and is opened to the radial innerside. The shuttle race body 2 has the shuttle race main body 14, and ashuttle body presser 15 which is detachably fixed to the shuttle racemain body 14. When the shuttle body presser 15 is detached from theshuttle race body 14, the track groove 7 is opened in one of the axialdirections.

FIG. 3 is a front view showing the shuttle body 3, FIG. 4 is a side viewshowing the shuttle body as seeing from the right side of FIG. 3, FIG. 5is a plan view as seeing from the upper side of FIG. 3, and FIG. 6 is arear view as seeing from the rear side of FIG. 3. Referring to FIGS. 1and 2 also, the shuttle body 3 is attached to the shuttle race body 2while its axis coincides with the axis L1 of the shuttle race body 2(hereinafter, also the axis of the shuttle body 3 is denoted by thereference symbol L1). The track projection 11 elongates about the axisL1 in the circumferential direction, and protrudes toward the radialouter side. The shuttle body 3 has: a peripheral wall 17 in which thetrack projection 11 is formed in the outer peripheral portion; a bottomwall 18 which is continuous from one axial end portion of the peripheralwall 17, and integrally formed along a virtual plane that isperpendicular to the axis L1; and a stud 19 which perpendicularlyprotrudes along the axis L1 from the center of the bottom wall 18 towardthe axial other end of the peripheral wall 17. The shuttle body isopened in the other end which is in the axial direction of the body withrespect to the bottom wall 18.

The peripheral wall 17 elongates over the whole periphery in thecircumferential direction, and has a peripheral wall portion 20 which ison the bottom wall 18 side with respect to the center in the axialdirection, and a wall portion 21 which is on the open end side withrespect to the center in the axial direction. The bottom wall-sideperipheral wall portion 20 is formed continuously with the bottom wall18. In regions S1 and S2 where the loop seizing beak 10 is formed withrespect to the circumferential direction, the bottom wall-sideperipheral wall portion 20 is formed into a cylindrical shape, and, inthe remaining region other than the regions S1 and S2 with respect tothe circumferential direction, formed into a truncated conical shape inwhich the diameter is larger as moving in the axial direction from thebottom wall 18 toward the open end.

In the region S1 of the bottom wall-side peripheral wall portion 20which elongates in both the sides of the position where the loop seizingbeak 10 is formed, the outer peripheral face near the bottom wall 18 isformed into the same shape as that of the truncated conical shape of theremaining region other than the regions S1 and S2. In the region S2 ofthe bottom wall-side peripheral wall portion 20 which is continuous tothe region S1 of the bottom wall-side peripheral wall portion 20 in theupstream side in a counterclockwise direction as seeing the shuttle body3 in the region S1 from the rear side, the outer peripheral face nearthe bottom wall 18 is formed into a truncated conical shape in the samemanner as the region S1, and that near the shuttle body open end isformed so as to more approach the truncated conical outer peripheralface of the remaining region other than the regions S1 and S2 as furthermoving toward the upstream side in the direction of the arrow B. Theregions S1 and S2 which are formed into a cylindrical shape extend in arange of about 60 deg. in the circumferential direction and centered ata position which is shifted toward the upstream side in the directionindicated by the arrow B from the position where the loop seizing beak10 is formed with respect to the circumferential direction. In thebottom wall-side peripheral wall portion 20, at least the portion nearthe bottom wall 18 smoothly elongates over the whole periphery in thecircumferential direction, and the outer peripheral face of the portionis formed into a truncated conical shape in which the diameter issmaller as moving from the open end toward the bottom wall 18.

The open-end peripheral wall portion 21 is continuous to the end of thebottom wall-side peripheral wall portion 20 which is opposite to theside that is continuous to the bottom wall 18, and formed into atruncated conical shape in which the diameter is smaller as moving inthe axial direction from the bottom wall 18 toward the open end. In aregion S3 which elongates in both the sides of the position where theloop seizing beak 10 is formed, with respect to the circumferentialdirection, a needle drop hole 22 which passes through in a radialdirection is formed in a portion near the bottom wall-side peripheralwall portion 20. The region S3 where the needle drop hole 22 is formedis formed in a range of about 220 deg. in the circumferential directionand centered at a position which is shifted toward the downstream sidein the direction of the arrow B or a clockwise direction as seeing theshuttle body 3 from the front side, from the position where the loopseizing beak 10 is formed with respect to the circumferential direction.In the open-end peripheral wall portion 21, at least the portion nearthe open end smoothly elongates over the whole periphery in thecircumferential direction, and the outer peripheral face of the portionis formed into a truncated conical shape in which the diameter issmaller as moving from the bottom wall 18 toward the open end.

The peripheral wall 17 has the thus configured peripheral wall portions20 and 21, and has a shape in which an axial center portion swellstoward the radial outer side. The track projection 11 is formed in theaxial center portion of the peripheral wall 17 so as to bulge toward theradial outer side. The track projection 11 is notched away to be dividedin a region S4 near the position where the loop seizing beak 10 isformed with respect to the circumferential direction, and, in theremaining regions S5 to S7, elongates continuously in thecircumferential direction. The region S4 where the track projection 11is notched away is in a range of about 30 deg. in the circumferentialdirection and centered at the position where the loop seizing beak 10 isformed, with respect to the circumferential direction.

In the track projection 11, a section taken along a virtual planeincluding the axis L1 has a substantially rectangular shape. The trackprojection has an inner peripheral portion 28 and an outer peripheralportion 29. The outer peripheral portion 29 more protrudes toward theopen end of the bobbin case holder than the inner peripheral portion 28.With respect to the width in the axial direction of the outer peripheralportion 29, the widths W1 of the regions S5 and S6 near the ends of thecircumferential direction are smaller than the width W2 of the region S7between the regions S5 and S6 in the circumferential direction.Therefore, the projection amounts of the regions S5 and S6 with respectto the inner peripheral portion 28 are smaller than the projectionamount of the region S7. The region which is a total of the region S4where the track projection is notched away, and the regions S5 and S6where the outer peripheral portion 29 has a smaller width substantiallycoincides with the region S3 where the needle drop hole 22 is formed,with respect to the circumferential direction.

An outer peripheral face 100 of the outer peripheral portion 29 whichserves as the outer peripheral face of the track projection 11 is formedas a cylindrical face, and bottom wall-side end faces 101, 102 of theportions 28 and 29 which serve as the end faces of the track projection11 on the bottom wall 18 side are formed as flat faces perpendicular tothe flush axis L1. An end face 103 of the inner peripheral portion 28 onthe side of the bobbin case holder open end which constitutes the endface of the track projection 11 on the bobbin case holder open end sideis formed as a flat face perpendicular to the axis L1. With respect toend faces of the outer peripheral portion 29 on the side of the bobbincase holder open end which constitute the end faces of the trackprojection lion the bobbin case holder open end side, the end faces 104,105 are inclinedly formed in the ends of the regions S5 and S6 near theregion S7, and the end faces 106, 107, and 118 are formed as flat facesperpendicular to the axis L1 in the remaining region other than theends.

An end face 110 of a portion of the open-end peripheral wall portion 21which faces the needle drop hole 22 from the bottom wall 18 side isformed in the same face as the end faces 106, 107 of the regions S5 andS6 of the outer peripheral portion 29 of the track projection 11 on theshuttle body open end side. In the region S4 where the track projection11 is notched away, the portion of the open-end peripheral wall portion21 on the bottom wall 18 side is formed into a cylindrical shape. In theregion S4 where the track projection 11 is notched away, therefore, theouter peripheral faces of the peripheral wall portions 20 and 21 in anintermediate portion between the axial ends are formed as the identicalcylindrical face about the axis L1.

A loop-seizing-beak-forming-portion 26 is integrally formed on theperipheral wall 17 so as to protrude from a circumferential one end 25of the track projection 11 which is an end on the downstream side in thedirection of the arrow B, and further in the direction of the arrow B.The loop seizing beak 10 is formed in theloop-seizing-beak-forming-portion 26. Theloop-seizing-beak-forming-portion 26 functions also as a trackprojection. The loop-seizing-beak-forming-portion 26 is formed in thedirection of the arrow B and the axial direction of the shuttle body 3so as to be tapered along the direction from the bottom wall 18 towardthe open end.

In the loop-seizing-beak-forming-portion 26, an outer peripheral face111 is formed on the same cylindrical face as the outer peripheral face100 of the track projection 11, an end face 113 of an inner peripheralface 112 on the side of the shuttle body open end is formed on the sameflat face as the end face 103 of the inner peripheral portion 28 of thetrack projection 11 on the side of the shuttle body open end, an endface 115 of a basal end 114 of the outer peripheral portion on the sideof the shuttle body open end is formed on the same flat face as the endfaces 106 and 107 in the regions S5 and S6 of the outer peripheralportion 29 of the track projection 11 on the shuttle body open end side,an end face 117 of a tip end 116 on the shuttle body open end side isformed on the same flat face as the end face 118 in the region S7 of theouter peripheral portion 29 of the track projection 11 on the shuttlebody open end side, and an end face on the bottom side is inclinedlyformed so that an end face 119 on the basal end is formed on the sameflat face as the end face on the bottom wall side of the trackprojection 11 and an end face 120 of the tip end further approaches theshuttle body open end from the bottom wall 18 as moving in the directionof the arrow B. The loop seizing beak 10 is formed at the tip end of inthe loop-seizing-beak-forming-portion 26. The loop seizing beak 10 ispositioned on a circle where a plane including the end face 118 on theshuttle body open end side in the region S7 of the outer peripheralportion 29 of the track projection 11 intersects with the cylindricalface including the outer peripheral face 100 of the track projection 11.

The shuttle body 3 has a spring member 35, which is disposed in a recess40 formed between the circumferential ends 25 and 38 of the trackprojection 11. The spring member 35 has a substantially L-like shape. Aportion 36 on the side of a basal end is placed along thecircumferential direction, and fixed by screws or the like to an outerperipheral portion of the cylindrically-shaped peripheral wall 17 in theregion S4 where the track projection is notched away. Under this state,a portion 37 on the free end side is outward projected in a radialdirection. The portion 37 on the free end side is placed in the recess40 of the peripheral wall including the circumferential other end 38 ofthe track projection 11, with forming a gap T1 with respect to the endwhich faces in the direction opposite to that of the arrow B and is onthe upstream side in the direction of the arrow B. According to thisconfiguration, the spring member 35 can be elastically deformed in thedirection of the arrow B. The spring member 35 is placed so as not toproject outwardly in the axial direction and a radial direction from amovement path of the track projection when the shuttle body 3 is rotatedabout the axis L1.

The bottom wall 18 is on a disk, and continuous integrally with thebottom-wall-side peripheral wall portion 20 of the peripheral wall 17over the whole periphery in the circumferential direction. A stud 19 iscontinuous integrally with the bottom wall 18, and perpendicularlyprotrudes from the bottom wall 18. The stud 19 has a substantiallycolumnar shape. An engaging groove 32 which elongates in thecircumferential direction is formed in the tip end portion. In the thusconfigured shuttle body 3, the peripheral wall 17, the bottom wall 18,and the stud 19 are integrally formed, and the spring member 35 is madeof spring steel or the like.

FIG. 7 is a horizontal section view showing the shuttle race body 2 andthe shuttle body 3 in a simplified manner. The shuttle race main body 14of the shuttle race body 2 has a peripheral wall 60, and a bottom 61which is continuous to one axial end of the peripheral wall 60. Apenetration hole 62 which is passed through in the axial direction isformed in the bottom 61. The shuttle body presser 15 has an annularshape, and is detachably attached to the peripheral wall 60 of theshuttle race main body 15 by screws or the like. The shuttle race body 2is opened on the side opposite to the bottom 61.

The shuttle body presser 15 is detached from the shuttle race main body14 to open the shuttle race body open end side of the track groove 7 inthe axial direction. Under this state, the track projection 11 is fittedinto the track groove 7, and the shuttle body presser 15 is attached tothe shuttle race main body 14 to attain a locked state. The shuttle body3 is then attached to the shuttle race body 2. The shuttle body 3 isattached while the bottom wall 18 is placed near the bottom 61 of theshuttle race main body 14. Under the state where the shuttle body 3 isattached to the shuttle race body 2, the shuttle body is guided by theportion where the track projection 11 faces the track groove 7, and theshuttle body is rotatable about the axis L1.

Referring to FIGS. 1, 2, and 7, the driver 4 has: the driver body 43comprising a pressing portion 42 which presses the shuttle body 3; and acylindrical boss 45 which is positioned in the circumferential directionand fixed to a lower shaft 44 of the sewing machine, and is disposed inthe shuttle race body 2. The boss 45 is placed behind the shuttle body3, and fixed to the lower shaft 44 which is passed through thepenetration hole 62 of the shuttle race main body 14 and elongates tothe vicinity of the shuttle body 3. The driver body 43 is formed into asubstantially L-like shape, and has: a basal portion 46 which isoutwardly elongated from an end of the boss 45 near the shuttle body 3in a radial direction, and along the bottom wall 18 of the shuttle body3; and the pressing portion 42 which is bent from a radial outer end ofthe basal portion 46 toward the open end of the shuttle body 3, andwhich elongates toward the open end of the shuttle body 3 in the axialdirection. The tip end portion of the pressing portion 42 is fitted intothe recess 40 of the shuttle body 3. Spaces respectively having gaps T2and T3 which are larger than the thickness (outer diameter) of theneedle thread 9 are formed between the pressing portion 42 of the driverbody 43 and the cylindrically formed peripheral wall 17 of the shuttlebody 3, between the basal portion 43 and the bottom wall 18 of theshuttle body 3, and between the boss 45 and the bottom wall 18 of theshuttle body 3. When the lower shaft 45 of the sewing machine iscontinuously rotated about the axis L3 in the direction of the arrow Aor a clockwise direction as seeing from the front side, the thusconfigured driver 4 is continuously rotated about the same axis L3 inthe same direction or the direction of the arrow A. When the driver 4 isrotated, the tip end of the pressing portion 42 of the driver body 43presses the spring member 35 of the shuttle body 3 in the direction ofthe arrow A, whereby the shuttle body 3 is rotated in the direction ofthe arrow B which is substantially identical with the rotation directionA of the driver 4.

The bobbin case 5 has a peripheral wall 47 on which a bobbin threadtension spring that is not shown is disposed, and an end wall 49 whichis perpendicularly continuous from one axial end of the peripheral wall47, and in which a latch mechanism 48 is disposed, and is opened on theside opposite to the end wall 49. The latch mechanism 48 has a latch 50which is displaceable in one diameter line direction, is urged by aspring force toward one side along the one diameter line, and can bedisplaced against the spring force by an operating piece 51. A part ofthe latch 50 is fitted into the engaging groove 32 of the stud 19 sothat the latch 50 is engaged to the stud 19. The bobbin case 5 isattached to the shuttle body 3 so as to be rotatable about the axis L1with respect to the shuttle body 3, while the axis of the bobbin case isset to coincide with the axis L1 of the shuttle body 3, and the end wall49 is placed on the shuttle body open end side.

In the bobbin case 5, a horn portion 53 is integrally formed whichelongates from the end wall 49 along a plane including the end wall 49,and in which a tip end portion 52 is bent toward the open end of thebobbin case 5 outside the peripheral wall 17 of the shuttle body 3.Under a state where the bobbin case 5 is attached to the shuttle body 3,the horn portion 53 is fitted into a locking recess (not shown) which isformed in the shuttle body presser 15 of the shuttle race body 2,thereby blocking the rotation about the axis L1 due to the rotation ofthe shuttle body 3. The positioning is performed under a state where thehorn portion 53 upwardly elongates.

The bobbin 6 is attached to the bobbin case 5 so as to accommodate thebobbin thread 12 wound around the bobbin 6, which bobbin case 5 isattached to the shuttle body 3 in a state where the bobbin 6 is attachedto the bobbin case 5 and the bobbin thread 12 is accommodated therein.The bobbin thread 12 accommodated in the bobbin case 5 is pulled outfrom the bobbin 6, passed between the peripheral wall 47 of the bobbincase and the bobbin thread tension spring, passed over the axial otherend of the shuttle body, passed through a through hole 55 formed in atip end portion 52 of the horn portion 53, and then guided to the upperside through a needle hole formed in the throat plate.

When the sewing operation is started, the driver 4 is rotated about theaxis L3 in the direction of the arrow A by the rotation of the lowershaft 44, and the shuttle body 3 is rotated about the axis L1 in thedirection of the arrow B. By the rotation of an upper shaft which is notshown and interlocked with the lower shaft 44, the needle 8 isvertically reciprocated along the axis L2 in synchronization with therotation of the shuttle body 3. A through hole 66 is formed in theneedle 8, and the needle thread 9 is passed through the hole. When theneedle 8 is placed in the vicinity of the lowest position as a result ofthe vertical reciprocation of the needle 8, therefore, the needle thread9 is supplied into the movement path of the loop seizing beak 10. Theshuttle body 3 and the needle 8 are positioned so that, when the needle8 is passed over the lowest position and then displaced slightlyupwardly, the loop seizing beak 10 is passed through the vicinity of themovement path of the needle 8. The needle thread 9 supplied by themovement path of the needle 8 is seized by the loop seizing beak 10.

The needle thread 9 seized by the loop seizing beak 10 is pulled in therotation direction B of the shuttle body 3 by theloop-seizing-beak-forming-portion 26, to form a loop of the needlethread. The loop of the needle thread 9 is moved over the periphery ofthe shuttle body 3 while being guided by the peripheral wall 17 of theshuttle body 3 to be extended, so that the two thread portions of theloop of the needle thread which vertically elongate are passed over thebottom wall side of the shuttle body 3, and the open end side of theshuttle body, respectively. In this way, until the loop seizing beak 10reaches the vicinity of the lowest point, the needle thread 9 is passedthrough the right side with respect to a virtual vertical planeincluding the axes L1 and L2 as seeing from the front side, anddownwardly pulled by the loop-seizing-beak-forming-portion 26 whilesliding over the outer surface of the shuttle body 3. When the loopseizing beak 10 reaches the vicinity of the lowest point, the needlethread 9 is pulled up by a thread take-up lever which is not shown, withpassing through the left side with respect to the virtual vertical planeincluding the axes L1 and L2 as seeing from the front side. In this way,the loop of the needle thread 9 is passed over the shuttle body 3, sothat the loop is passed over the bobbin case 5 attached to the inside ofthe shuttle body 3. As a result, the needle thread 9 is wound around thebobbin thread 12 pulled out from the bobbin case 5, and a stitch is thenformed. When the shuttle body 3 is further rotated and the loop seizingbeak 10 reaches the vicinity of the movement path of the needle 8, theneedle thread 9 is again supplied by the needle 8, and theabove-described operation is repeated to continuously form stitches,whereby a workpiece on the throat plate can be sewn.

In the full rotary hook 1 according to the invention, since the shuttlebody 3, which seizes the needle thread 9 and moves the loop of theneedle thread 9 while expanding it, is rotated by the driver 4 which isseparately formed, the needle thread 9 can be passed over the shuttlebody 3 when the thread is passed over the bobbin case 5. Therefore, theloop of the needle thread 9 can be passed over the bobbin case 5 under astate where the loop is expanded into a substantially U-like shapewithout crossing in an intermediate portion, and the needle thread 9 iswound around the bobbin thread 12 without forming a twist. The driver 4is continuously rotated in the predetermined rotation direction A, and,in accordance with the rotation, the shuttle body 3 is continuouslyrotated. The driver 4 and the shuttle body 3 do not stop during anoperation of one cycle, and hence the full rotary hook 1 can be operatedat a high speed to increase the sewing speed.

In the full rotary hook 1, the needle drop hole 22 is formed in theopen-end peripheral wall portion 21 of the peripheral wall 17, and, whenthe needle 8 is downwardly displaced in order to place the needle thread9 in the vicinity of the movement path of the loop seizing beak 10, itis possible to prevent the needle 8 from interfering with the peripheralwall 17 of the shuttle body 3. This will be described in detail asfollows. In the embodiment, the shuttle body 3 and the needle 8 aredisposed so as to be in synchronism with each other so that, when theneedle 8 is passed over the lowest position and then displaced slightlyupwardly, the loop seizing beak 10 is passed through the vicinity of themovement path of the needle 8. With respect to the shuttle body 3, thetip end of the needle 8 is passed through a movement path 70 which isindicated by the phantom line in FIG. 2. Therefore, the needle drop hole22 is formed in the region S3 configured as described above so that themovement path 70 does not intersect with the peripheral wall portion 21,thereby preventing interference between the shuttle body 3 and theneedle 8 from occurring.

Since the needle 8 is vertically moved in the vicinity of the trackprojection 11, the track projection 11 is notched away or the width W ofthe outer peripheral portion 29 of the track projection 11 is selectedso as to be small, in the regions S4 to S6 which substantially coincidewith the region S3 where the needle drop hole 22 is formed. Interferencebetween the shuttle body 3 and the needle 8 is prevented also by thisconfiguration from occurring. More specifically, in the region S4, thetrack projection 11 is notched away, and hence interference with theneedle 8 does not naturally occur. In the regions S5 and S6, theirwidths W1 are selected so as to be smaller than the width W2 of theregion S7 and the amount of projection toward the shuttle body open endis small, and, in other words, the end faces 106 and 107 in the regionsS5 and S6 are more retracted toward the bottom wall 18 of the shuttlebody than the end face 118 in the region S7, thereby preventinginterference between the needle 8 and the track projection 11 fromoccurring. As described above, in both the sides of the loop seizingbeak 10 with respect to the circumferential direction, the trackprojection 11 is notched away or retractively formed so as to avoidinterference with the needle 8. In addition, in the tip end portion 116of the outer peripheral portion of the loop-seizing-beak-forming-portion26, the end face 117 on the shuttle body open end side more protrudestoward the shuttle body open end side than the end faces 106 and 107 inthe regions S5 and S6 on the shuttle body open end side, in the samemanner as the end face 118 on the shuttle body open end side in theregion S7 of the outer peripheral portion 29 of the track projection 11.The needle thread 9 supplied by the needle 8 is seized by the loopseizing beak 10 which is formed in the plane including the protrudingend faces 117 and 118. Since the loop-seizing-beak-forming-portion 26 ispassed through a recess 120 formed in the needle 8, the portion does notinterfere with the needle 8.

In the embodiment, the axial center portion of the peripheral wall 17 ofthe shuttle body 3 more swells toward the radial outer side than theremaining portion, and the peripheral wall has the peripheral wallportions 20 and 21 formed into a truncated conical shape in which thediameter is smaller as moving from the axial center portion toward theaxial ends, and the outer peripheral face of a truncated conical shapein which the diameter is smaller as moving toward the axial ends.Furthermore, the loop-seizing-beak-foriming-portion 26 where the loopseizing beak 10 for seizing the needle thread 9 is formed is formed inthe axial center portion which swells toward the outer side in a radialdirection, and, with respect to the loop of the needle thread 9 seizedby the loop seizing beak 10, the two needle thread portions whichvertically elongate are smoothly guided and expanded by the outerperipheral face of the peripheral wall 17 toward the bottom wall 18 sideand the shuttle body open end side, respectively. Therefore, the loop ofthe needle thread 9 can be smoothly passed over the shuttle body 3. Ineach of the peripheral wall portions 20 and 21, at least the portionswhich are positioned at the axial ends of the peripheral wall 17continuously elongate over the whole periphery in the circumferentialdirection, and their outer peripheral faces are formed into a truncatedconical shape such as that described above. Therefore, the loop of theneedle thread 9 is prevented from being caught by the shuttle body 3when the loop is passed over the hook. The angles θ1 and θ2 formed bythe axis L1 and the outer peripheral faces of the peripheral wallportions 20 and 21 which are formed into a truncated conical shape havethe same value of, for example, about 45 to 48 deg. Each of the needlethread portions of the loop of the needle thread 9 which is guided bythe peripheral wall portions 20 and 21, is enabled to perform the threadpassing while being passed over at substantially the same timing theposition on the bottom side, and that on the shuttle body open end sidewhich correspond to each other in the axial direction of the shuttlebody, respectively.

In the full rotary hook 1, the shuttle body 3 is rotated while thedriver 4 presses the portion 37 on the free end side of the springmember 35 of the shuttle body 3. When the driver 4 is continuouslyrotated and the shuttle body 3 is rotated, therefore, the spring member35 periodically repeats an elastic deforming operation and a recoveringoperation from the elastic deformation. Consequently, the driver 4 andthe portion 37 on the free end side of the spring member 35 periodicallyabut against and separate from each other, or, as shown in FIG. 8, havea time period when they separate from each other, and a time period t2when they abut against each other in one cycle t1 of the operation ofthe full rotary hook 1. When the loop of the needle thread 9 is to bepassed over the shuttle body 3, the loop can be passed through the gapbetween the driver 4 and the portion 37 on the free end side of thespring member 35 at the timing when the driver 4 separates from theportion 37 on the free end side of the spring member 35. When the loopof the needle thread 9 is to be passed over the shuttle body 3,therefore, the needle thread 9 can be prevented from being pressedbetween the shuttle body 3 and the driver 4 to be caught thereby, andthe loop of the needle thread 9 can smoothly perform the thread passing.Even when the needle thread 9 is accidentally pressed between theshuttle body 3 and the driver 4, the needle thread 9 elastically deformsthe spring member 35 and can be then passed between the driver 4 and thespring member 35. Therefore, a breakage of the needle thread 9 does notoccur.

By selecting spring constant of the spring member 35, it is possible toselect the time period t2 when the tip end portion of the pressingportion 42 of the driver 4 abuts against the portion 37 on the free endside of the spring member 35.

In the full rotary hook 1, the rotation axis L3 of the driver 4 iseccentric with respect to the rotation axis L1 of the shuttle body 3. Inthe embodiment, the rotation axis L3 is eccentric with respect to therotation axis L1 so as to be slightly shifted to the lower right asseeing from the front side. When the axes L1 and L3 are eccentric witheach other as described above, the position where the driver 4 pressesthe shuttle body 3 is changed in a radial direction of the shuttle body3, so that the torque transmitted from the driver 4 to the shuttle body3 is periodically changed. As a result, at a time when the torque islow, the loop of the needle thread is allowed to pass between the driverand the shuttle body.

By selecting direction and amount of eccentricity of the axes L1 and L3,it is possible to select the timing when the pressing portion 42 of thedriver 4 separates from the portion 37 on the free end side of thespring member 35 during one cycle of the operation of the full rotaryhook 1. Therefore, the pressing portion 42 of the driver 4 can surelyseparate from the portion 37 on the free end side of the spring member35 when the needle thread 9 is pulled up by the thread take-up lever andthe needle thread is passed between the driver 4 and the spring member35.

In the full rotary hook 1, the shuttle body 3 has the peripheral wall onwhich the track projection is formed, and the loop of the needle threadseized by the loop seizing beak is moved along the periphery of theshuttle body while being guided and expanded by the peripheral wall, sothat the loop of the needle thread can be easily passed over the shuttlebody and the bobbin case. The needle drop hole into which the needle isto be inserted is formed in the peripheral wall, thereby preventing theneedle and the shuttle body from interfering with each other.

FIG. 9 is an enlarged section view showing a section IX of FIG. 7. Asdescribed above, the full rotary hook 1 is configured so that theshuttle body 3 is rotated by the driver 4 which is separately formed,and the shuttle body 3 is not fixed to the lower shaft or the like ofthe sewing machine, and therefore the shuttle body is easily displacedin the shuttle race body 2 in a radial direction perpendicular to theaxis L1. When the shuttle body 3 is rotated by the driver 4, therefore,the shuttle body vibrates in a radial direction. Furthermore, thecutaway portion for needle drop is formed in the track projection 11,and hence vibration is easily generated. In order to prevent suchvibration from being generated, protrusions 72 and 73 are formed in theshuttle race body 2 and shuttle body 3 of the full rotary hook 1,respectively.

In the shuttle race body 2, the protrusion 72 is formed on the shuttlebody presser 15. The protrusion 72 protrudes in the radial inner side ofthe track groove 7 and toward the bottom 61 of the shuttle race mainbody 14 in the axial direction. The protrusion 72 elongates in thecircumferential direction, and hence the track groove 7 has a recess 74which elongates in the radial outer side of the protrusion 72 and in thecircumferential direction. In this way, with respect to end faces of theshuttle body presser 15 which face the track groove 7 and serve as endfaces that face the track groove 7 of the shuttle race body 2 from theshuttle race body open end side, an end face 121 on the radial innerside more protrudes toward the bottom 61 of the shuttle race body 2 thanan end face 122 on the radial outer side, and is formed as a flat faceperpendicular to the axis L1. An outer peripheral face 75 of theprotrusion 72 on the radial outer side is formed as a cylindrical faceabout the axis L1. An inner peripheral face 123 of the shuttle race mainbody 14 which faces the track groove 7 from the radial outer side isformed as a cylindrical face, and an end face 124 which faces the trackgroove 7 from the bottom 61 of the shuttle race body 2 is formed as aflat face perpendicular to the axis L1.

As described above, the track projection 11 of the shuttle body 3 hasthe inner peripheral portion 28 and the outer peripheral portion 29. Theouter peripheral portion 29 more protrudes toward the open end of theshuttle body than the inner peripheral portion 28. In the trackprojection 11 of the shuttle body 3, therefore, the protrusion 73 isformed on the radial outer side. The protrusion 73 protrudes toward theopen end of the shuttle body in the axial direction of the shuttle body3. The protrusion 73 elongates in the circumferential direction. In thetrack projection 11, therefore, a recess 76 which elongates in theradial inner side of the protrusion 73 and in the circumferentialdirection is formed. An inner peripheral face 77 of the protrusion 73 onthe radial inner side is formed as a cylindrical face about the axis L1.

The track projection 11 is fitted into the track groove 7 in a statewhere the protrusion 73 is fitted into the recess 74 and the protrusion72 is fitted into the recess 76. The shuttle body 3 is attached to theshuttle race body 2 while the track projection 11 is fitted into thetrack groove 7 in this way. As described above, in order to avoidinterference with the needle 8, the projection 11 in which theprojection amounts of the regions S5 and S6 toward the shuttle body openend side and in the vicinity of the circumferential ends of the outerperipheral portion 29 of the track projection 11 are made smaller isguided by the portion facing the track groove 7, and rotated about theaxis L1. When the shuttle body 3 is rotated by the driver 4 in this way,the inner peripheral face 77 of the protrusion 73 of the shuttle body 3is supported by the outer peripheral face of he protrusion 72 of theshuttle race body 2, and the protrusion 73 of the shuttle body 3 isengaged to the protrusion 72 of the shuttle race body 2 from the radialouter side of the shuttle body 3. The outer diameter of the outerperipheral face 75 of the protrusion 72 is selected so as to be slightlysmaller than the inner diameter of the inner peripheral face 77 of theprotrusion 73. Under a state where the shuttle body 3 is attached to theshuttle race body 2, the gap between the faces 75 and 77 is as small asabout two to three hundredths mm. Therefore, the shuttle body 3 issmoothly guided in the circumferential direction under a state wheredisplacement in a radial direction is blocked. Consequently, the shuttlebody 3 is stably rotated about the axis L1 while vibration in a radialdirection during rotation is prevented from being generated, wherebyhook noises are prevented from being generated at a high level. In thecycles of the full rotary hook 1, furthermore, the needle thread 9behaves constantly, so that uniform stitches can be formed.

The full rotary hook 1 can be realized by slightly modifying anoscillating loop taker which has been already existing and described inthe paragraph of Background Art, and a sewing machine comprising it. Inthe full rotary hook 1, it is requested only that the protrusion 72 isformed on a shuttle body presser of an existing shuttle race body, anexisting shuttle body and an existing driver are replaced with theshuttle body 3 and the driver 4 described above, and a mechanism forconverting a rotation to a half rotation is removed away from a drivingsystem for driving a lower shaft of an existing sewing machine. A sewingmachine is not necessary to be largely remodeled.

The embodiments described above are only examples of modes for carryingout the invention, and can be modified to other configurations withinthe scope of the invention. For example, the axis L2 of the movementpath of the needle 8 may not be perpendicular to the rotation axis L1 ofthe shuttle body 3. As the spring member 35, another spring such as acompression coil spring, a tension coil spring, or a belleville springmay be used in place of the above-mentioned plate spring. Spring meanswhich is configured not by a single spring but by a combination of aspring and another component such as a member for holding the spring maybe used. Also these alternatives can attain the same effects. Theprotrusions 72 and 73 which are formed in the shuttle race body 2 andthe shuttle body 3 may be formed on the bottom wall 18 side of theshuttle body 3 which is on the bottom side of the shuttle race body 2,or on both the sides in the axial direction, with attaining the sameeffects. The rotation axis L1 of the shuttle body 3 and the rotationaxis L3 of the driver 4 may be coaxially placed. The peripheral wall 17may be asymmetrically formed with respect to the track projection 11positioned in an axial center portion, by, for example, selecting theinclination angles θ1 and θ2 of the peripheral wall portions 20 and 21of the shuttle body 3 with respect the axis L1 to have different values,so that the passing timings of the thread portions of the loop of theneedle thread 9 which vertically elongate may be different from eachother on the sides of the bottom wall 18 and the open end of the shuttlebody 3. As shown by the phantom line 80 in FIG. 4, the peripheral wall17 of the shuttle body 3 may be formed into a substantially cylindricalshape to round the axial end portions, whereby the outer diameter of theattachable bobbin case 5 is made larger without increasing the wholeouter diameter dimension of the shuttle body 3, thereby enhancing theaccommodation capacity of the bobbin thread 12. Even when the peripheralwall 17 is formed into a substantially cylindrical shape as describedabove, the needle thread 9 can be smoothly guided toward the bottom wall18 and the shuttle body open end so as to achieve smooth thread passing,because the axial end portions are rounded. In this way, the details ofthe full rotary hook 1 may be adequately modified.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription and all changes which come within the meaning and the rangeof equivalency of the claims are therefore intended to be embracedtherein.

Industrial Applicability

According to the invention set forth in claim 1, the shuttle body whichseizes the needle thread and moves the loop of the needle thread whileexpanding the loop is rotated by the driver which is separately formed.When the loop of the needle thread is to be passed over the bobbin case,therefore, the loop can be passed over the shuttle body. Consequently,the loop of the needle thread can perform the thread passing under astate where the loop is expanded into a substantially U-like shapewithout crossing in an intermediate portion, and the needle thread iswound around the bobbin thread without forming a twist. The driver iscontinuously rotated in a predetermined rotation direction, and, inaccordance with the rotation, the shuttle body is continuously rotated.The driver and the shuttle body do not stop during an operation of onecycle, and hence the full rotary hook can be operated at a high speed.

The track projection has the inner peripheral portion and the outerperipheral portion, and the outer peripheral portion protrudes towardthe shuttle body open end with respect to the inner peripheral portionto form the protrusion. In the outer peripheral portion of the trackprojection, the projection amount with respect to the inner peripheralportion in the regions near the circumferential ends is smaller than theprojection amount with respect to the inner peripheral portion in theregion of the circumferential intermediate portion which is between theregions near the circumferential ends. Theloop-seizing-beak-forming-portion is formed so as to protrude in therotation direction of the shuttle body from the one circumferential endof the track projection which is placed on the downstream side in therotation direction of the shuttle body. Theloop-seizing-beak-forming-portion functions also as the track projectionwhich is fitted into the track groove. The loop-seizing-beak formed atthe tip end of the loop-seizing-beak-forming-portion is formed in theplane including the end face on the shuttle body open end side in theregion of the circumferential intermediate portion of the outerperipheral portion of the track projection.

As described above, the regions near the circumferential ends of theouter peripheral portion of the track projection are formed so as tohave a small width and a small projection amount toward the shuttle bodyopen end. According to this configuration, the needle which verticallymoves in the vicinity of the track projection is prevented frominterfering with the shuttle body. Although the loop seizing beak isformed in the plane including the end face on the shuttle body open endside in the region of the circumferential intermediate portion of theouter peripheral portion of the track projection, and theloop-seizing-beak-forming-portion protrudes toward the shuttle body openend, the loop-seizing-beak-forming-portion is passed through the recessformed in the needle, and hence does not interfere with the needle.

In the shuttle race body, the protrusion is formed to protrude towardthe track groove, and the recess is formed on the radial outer side ofthe protrusion. In the track projection of the shuttle body, theprotrusion is formed by the outer peripheral portion, and the recess isformed on the radial inner side of the protrusion. The protrusion of theshuttle race body is fitted into the recess of the track projection ofthe shuttle body, and the protrusion of the track projection of theshuttle body is fitted into the recess of the shuttle race body, andengaged with the protrusion of the shuttle race body from the radialouter side. Under this state, the track projection of the shuttle bodyis fitted into the track groove of the shuttle race body. The trackprojection of the shuttle body, in which the projection amount in theregions near the circumferential ends of the outer peripheral portion ofthe track projection is formed so as to be small in order to avoidinterference with the needle, is guided by the portion facing the trackgroove of the shuttle race body, and the shuttle body is rotatable aboutits axis. Furthermore, the shuttle body is prevented from vibrating in aradial direction during rotation, and can be stably rotated.

According to the invention set forth in claim 2, when the driver iscontinuously rotated, the spring member periodically repeats an elasticdeforming operation and a recovering operation from the elasticdeformation. This causes the driver and the free end of the spring memberor the vicinity of the free end to periodically abut against andseparate from each other. When the loop of the needle thread is to bepassed over the shuttle body, the loop can be passed through the gapbetween the driver and the free end of the spring member or the vicinityof the free end during a period when the driver and the free end of thespring member or the vicinity of the free end are separated from eachother. When the loop of the needle thread is to perform the threadpassing, therefore, the needle thread can be prevented from beingpressed between the shuttle body and the driver to be caught thereby,and the loop of the needle thread can smoothly perform the threadpassing. Even when the needle thread is accidentally pressed between theshuttle body and the driver, the needle thread elastically deforms thespring member and can be then passed between the driver and the springmember. Therefore, a breakage of the needle thread does not occur.

According to the invention set forth in claim 3, the position where thedriver presses the shuttle body is changed in the radial direction ofthe shuttle body, so that the torque transmitted from the driver to theshuttle body is periodically changed. As a result, the rotation speed ofthe shuttle body can be periodically changed, and the passing timing ofthe loop seizing beak in the circumferential direction can be changed.

According to the invention set forth in claim 4, the shuttle body hasthe peripheral wall on which the track projection is formed, and theloop of the needle thread seized by the loop seizing beak is moved alongthe periphery of the shuttle body while being guided and expanded by theperipheral wall, so that the loop of the needle thread can be easilypassed over the shuttle body and the bobbin case. The needle drop holeinto which the needle is to be inserted is formed in the peripheralwall, thereby preventing the needle and the shuttle body frominterfering with each other.

What is claimed is:
 1. A full rotary hook comprising: a shuttle racebody which is fixed to a body of a sewing machine and has a track grooveformed on an inner peripheral portion of the shuttle race body so as tocircumferentially elongate in a circumferential direction thereof; ashuttle body having a track projection elongating in the circumferentialdirection and being divided in the circumferential direction, formed onan outer peripheral portion, which track projection is fitted into thetrack groove to rotatably attach the shuttle body to the shuttle racebody, and in which a loop-seizing-beak-forming-portion is formed, theloop-seizing-beak-forming-portion including a loop seizing beak formedat a tip end thereof, for seizing a needle thread supplied by a needlewhich is vertically reciprocated; a driver which is continuously rotatedin synchronization with a vertical motion of the needle in apredetermined rotation direction, for rotating the shuttle body about anaxis of the shuttle body by pressing the shuttle body by rotation of thedriver; and a bobbin case for accommodating bobbin thread, beingdetachably attached to the shuttle body, wherein theloop-seizing-beak-forming-portion is formed so as to protrude in arotation direction of the shuttle body from one circumferential end ofthe track projection which is placed on a downstream side in therotation direction of the shuttle body, in the shuttle race body, aprotrusion which protrudes in an axial direction of the shuttle racebody with facing the track groove is formed, and a recess whichelongates in the circumferential direction is formed on a radial outerside of the protrusion, the track projection of the shuttle body has aninner peripheral portion and an outer peripheral portion, the outerperipheral portion more protruding toward an open end of the shuttlebody than the inner peripheral portion, a protrusion being formed by theouter peripheral portion, and a recess which elongates in thecircumferential direction being formed on a radial inner side of theprotrusion, the protrusion of the shuttle race body is fitted into therecess of the track projection of the shuttle body, the protrusion ofthe shuttle body being fitted into the recess of the shuttle race body,and engaged with the protrusion of the shuttle race body from a radialouter side of the shuttle body, in the outer peripheral portion of thetrack projection, a projection amount with respect to the innerperipheral portion in regions near circumferential ends is smaller thana projection amount with respect to the inner peripheral portion in aregion of a circumferential intermediate portion which is between theregions near the circumferential ends, and the loop seizing beak isformed in a plane including an end face on a side of a shuttle body openend in the region of the circumferential intermediate portion of theouter peripheral portion of the track projection, and theloop-seizing-beak-forming portion which more protrudes toward theshuttle body open end than the regions near the circumferential ends ofthe outer peripheral portion of the track projection is passed through arecess formed in the needle.
 2. The full rotary hook according to claim1, wherein the shuttle body has a spring member which is fixed in avicinity of a basal end, and the driver presses a free end of the springmember or a vicinity of the free end.
 3. The full rotary hook accordingto claim 1, wherein a rotation axis of the driver is eccentric withrespect to a rotation axis of the shuttle body.
 4. The full rotary hookaccording to claim 1, wherein the shuttle body has a peripheral wall onwhich the track projection is formed, a needle drop hole is formed in aregion of the peripheral wall where the needle is to be inserted towardthe shuttle body open end, and an end face which faces the needle drophole from the bottom of the shuttle body is formed in a same plane as anend face on a side of the shuttle body open end of the outer peripheralportion of the track projection in a region near the loop seizing beak.